颗粒粒径对微生物固化珊瑚砂的影响

Influence of Particle Sizes of Coral Sand on Bio-cementation

为了确定微生物固化珊瑚砂的最佳粒径范围,提高固化效果,选取5组不同单一粒径的珊瑚砂试样进行微生物固化试验,通过固化后珊瑚砂试样的表观特征分析、渗透性改变对比,以及利用环境扫描电镜对固化后的珊瑚砂颗粒进行微观扫描,以此综合分析颗粒粒径对微生物固化珊瑚砂的影响。试验表明,中等粒径(0.075 mm^2 mm)的珊瑚砂试样固化效果较好,特别是中砂(0.25 mm^0.5 mm)试样,经固化后整体性最好,无侧限抗压强度达到2.61 MPa,经微观照片显示,珊瑚砂颗粒表面被一层形状不规则且带棱角的碳酸钙结晶包裹,这些结晶填充了颗粒之间的部分孔隙;粗粒径(大于2 mm)和细粒径(小于0.075 mm)的珊瑚砂试样,由于其颗粒间孔隙和渗透性等因素导致固化效果较差。

In order to determine the optimal size range of coral sand for bio-cementation and improve the effect of bio-cementation, five groups of different particle sizes were selected to analyze the influence of different particle sizes of coral sand on bio-cementation were conducted by analyzing the apparent characteristics of biocemented coral sand samples, contrasting the change of permeability of biocemented coral sand samples and scanning microscopic structure of coral sand by environment scanning electron microscope. The tests indicate that the biocementing effect of medium size （0.075 mm - 2 mm） coral sand samples is better, especially for medium sand （0.25 mm - 0.5 ram） works best, and the unconfined compressive strength is 2.61 MPa. According to the microscopic photographs, particles of coral sand are wholly surrounded by a large number of irregular and angular calcium carbonate crystals after biocementing, and part of intergranular pores are fillered by the calcium carbonate. Because of the factors of pores between particles and permeability of coral sand et al, biocementing effect of large size （particle size is greater than 2 rnm） and small size （particle size is less than 0.075 mm） coral sand is poorer.